499
FXAK68 PAFC 191302
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
502 AM AKDT Sun May 19 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)...

A strong and unseasonably cool upper level trough extending south
and east from the the Gulf of Anadyr to the Central Gulf of
Alaska will weaken and lift north and east today as a strong
shortwave rotating around the trough moves east through the
Central Gulf of Alaska today and over the Panhandle on Monday.
Weak ridging builds into the Western Gulf of Alaska on MOnday.

On the surface a 1001 mb low currently located approximately 50
nm east of Kodiak City will continue to weaken this morning as it
pushes to the east into the Central Gulf today and into the
Eastern Gulf tonight. A front wrapping around the low continues
to push slowly north and is near Homer at this time. Strong
southeasterly winds ahead of the front will diminish later this
morning especially through Turnagain and Knik Arms where
southeast wind gust in the 25 to 35 mph range continue early this
morning. Rain has diminished over Kodiak Island as the front
passed to the north. Expect unsettled conditions over Southcentral
today with the rain over the Eastern Kenai and Prince William
Sound slowly diminishing from south to north today as the front
continues to weaken push north and east. Copper River Basin will
remain unsettled with clouds and showers expected through the day.
Winds, clouds and precipitation will decrease late Monday and
into Tuesday as a weak ridge builds into the northern Gulf of
Alaska.

A low over the Bering pushes another front into Southcentral
Tuesday morning, with rain likely overspreading much of
Southcentral by late Tuesday afternoon. A more southerly/southwesterly
flow aloft as compared to an easterly/southeasterly flow aloft with
this next low will bring a better chance of rain to the the
western Kenai, Anchorage Bowl, and MatSu areas.

-CC

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE
ALEUTIANS (Days 1 through 3: Today through Tuesday night)...

Due to good model consensus and run-to-run consistency, few
changes have been made to the forecast through Monday. By Tuesday,
however, forecast confidence diminishes as models differ on the
evolution and timing of an occluding Bering Sea low. As such, there
may be shifts in wind speed as well as precipitation timing and
amounts in subsequent forecast updates.

The negatively tilted trough and upper-level low that brought
much of yesterday`s weather will continue to move eastward into
the Gulf of Alaska through today. Shower activity over Southwest
Alaska should largely taper off through today, though the
combination of daytime heating and weak shortwaves wrapping around
the low could lead to isolated to widely scattered afternoon
showers.

Out west, a series of Kamchatka lows and fronts will begin to
impact the Bering Sea and Aleutian Chain. The first frontal system
is currently over the Western and Central Bering/Aleutians
spreading rain and winds up to 25 kt as it moves to the east.
The second system, a Kamchatka low, moves across the Western
Bering through today, merging with the first system as it
reaches the Pribilof Islands. This now energized front will bring
light to moderate rain and small craft winds as it sweeps east
across the Bering Sea, reaching the coast of Southwest Alaska
around midday Monday.

As the front moves into Southwest Alaska for the second half of
Monday, coastal Southwest Alaska will initially see the brunt of
precipitation. However, by late Monday night into early Tuesday
morning, an incoming stout shortwave will intensify rainfall and
progress the front eastward across Southern Alaska. Cold air aloft
moves in behind the front, keeping showers over parts of the
Bering/Aleutians and over much of Southwest Alaska through Tuesday.

-DAN/KC

&&

.LONG TERM FORECAST (Days 4 through 7)...

A persistent northwest to southeast oriented longwave trough will
remain over the Bering with a shortwave on the southern terminus bending
into the northern Gulf through Sunday. A second upper level low
will move from Kamchatka into the central Bering on Tuesday
followed by a third on Thursday. This series of low pressure
systems will bring gusty wind, coastal rain showers and interior
cloudy and isolated rain showers. Toward the end of next week, an
area of high pressure will push from the North Pacific into the
Bering Sea and nudge the longstanding trough eastward.


&&

.AVIATION...

PANC...VFR conditions will persist. Strong southeasterly winds
out of Turnagain are expected to persist past midnight tonight. It
does look like the Turnagain Arm winds will then turn down the
Inlet as a low moves along the southern Kenai Peninsula overnight
and turns the pressure gradient down-Inlet. There is the potential
for some wind shear when this happens, but it will likely be above
2000 ft.

&&


$$